The Oakland A's consider their farm system to be split into two different worlds. There are the lower levels, geared toward developing the skills of prospects, and a second standard, where players are groomed to become Major League-ready.

It's an interesting combination, because the A's have some top prospects who were first-round picks, like Jemile Weeks and Grant Green, who've been through the system and require additional seasoning. And then there are others like Brandon Moss, who made the jump last year after proving his worth and paying his dues in the Minors.

"We do, as a Major League organization, rely on our Triple-A club for development and to be able to step up when in need," said A's director of player development Keith Lieppman. "It's been a good year as far as supplementing the big league club and also developing at the lower levels."

And because of Oakland's reliance on its young guns, last weekend's First-Year Player Draft was vital to replenishing the well the A's have gone to again and again when in need.

The A's welcomed 42 players, including 23 pitchers, to the organization over the three-day event, and they hope the newest crop will fill the void left by players making the final step to the Major Leagues.

A number of the A's big league pitchers are merely a year removed from their Minor League roots, such as A.J. Griffin, Jarrod Parker, Dan Straily and Sean Doolittle, which is encouraging for other Oakland prospects nearing the jump.

One of those players is Addison Russell, the A's top prospect who has raced through Oakland's system just one year after being drafted with their 2012 first-round pick.

"Three levels in your first year playing is a lot," Lieppman said. "So we went and pushed him another level so it challenged him enough to where he's starting to have to make some adjustments. His tools are enough to succeed at the Major League level. We're just trying to speed him up so he can get through the system quickly."

Michael Choice has also made strides after spending much of last season injured in Double-A. Lieppman said Choice has made the biggest adjustment of any player in Oakland's farm system, and he's put himself in a position to be considered to play in the Majors.

"That's really what its all about," Lieppman said. "The tools are there. It's how well you can adjust to the upper levels."

The 23 pitchers selected in 2013 suggest that Oakland felt its farm system lacked enough pitching talent, especially considering that many teams believe there's no such thing as too many quality arms. The A's, however, rarely draft based on need, opting to select the player deemed most talented on their Draft board instead.

"That's really been our emphasis as long as I've been with the club," said Michael Holmes, who joined the A's in 2004 and has served as their assistant scouting director since '09. Drafting for need is faulty logic, Holmes said, because the players drafted today may not be needed two or three years down the road.

Of course, not every player reaches that final destination. Such was the case with Chad Lewis, Oakland's fourth-round selection in 2010. Lewis entered the A's organization a prospect with power potential who could one day become their everyday third baseman after batting .395 with four home runs and 24 RBIs in his senior year of high school.

But Lewis was never able to make the proper adjustments necessary to progress to the Major Leagues. He was released in May after hitting .200 for the Beloit Snappers and will have to join another organization or play in an independent league if his professional career is to continue.

"The things that were geared toward his style of play never came to fruition," Lieppman said. "At some point in the baseball world, you have to make decisions quickly on people, and if they're not there, you just move ahead."

Other times, it's just a matter of limited vacancy. The fact that the A's have won 18 of their last 23 games and are battling for their second straight division title suggests that Oakland is having success with its current roster and isn't in need of much help. Sometimes, all a player can do is hope they'll be considered when rosters expand in September.

"Sometimes you force it; players do so well that they force themselves to the next level," Lieppman said. "Occasionally, that's the case. The game's funny that way. A person like [A's third baseman Josh] Donaldson, he was up and down two or three times, and then opportunity is right and he just goes off."

Lieppman said Green could be the same as Donaldson in the future, just waiting to take off.

Green joining the Major League club would make him a rarity in the context of the A's current makeup. He would be the sole homegrown position player on Oakland's current roster, with only three pitchers drafted by the A's.

Lieppman said limited weight should be placed on those figures, saying the players selected by general manager Billy Beane and the A's scouts have been used to acquire the players that are currently fighting for a second straight playoff berth.

"I think we've had probably more players in the big leagues than any organization over the past few years," Lieppman said. "Whether they've played for us or other clubs, we're acquiring talent [along] with the talent we've developed. If they're playing for Oakland or somebody else, as long as we're getting the kind of players we need to win in Oakland, we're happy with that scenario."

Jeff Kirshman is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.